Named after the two-faced roman god, Janus particles have gained much attention due to their potential in a variety of applications, including drug delivery. This is the first book devoted to Janus particles and covers their methods of synthesis, how these particles self-assemble, and their possible uses. By following the line of synthesis, self-assembly and applications, the book not only covers the fundamental and applied aspects, but it goes beyond a simple summary and offers a logistic way of selecting the proper synthetic route for Janus particles for certain applications. Written by pioneering experts in the field, the book introduces the Janus concept to those new to the topic and highlights the most recent research progress on the topic for those active in the field.